Method of and device for making letter envelopes



W. DOETSCH May 7, 1957 l METHOD OF AND DEVICE FOR MAKING LETTERENVELOPES Filed Sept. 8. 1953 3 Sheejts-Sheet 1 1 May 7, 1957 w. DOETSCH2,791,161

METHOD OF' AND DEVICE'FOR MAKING LETTER ENVELOPES Filed Sept. 8, 1953 3Sheets-Sheet 2 mhh I ,igmlu L 1111 May 7, *1957 Filed Sept. 8. 1955 W.DOETSCH METHOD OF AND DEVICE FOR MAKING LETTER ENVELOPES 3 Sheets-Sheet3 nite METHOD F AND DEVICE FOR MAKING LETTER ENvELoPEs The presentinvention relates to envelopes and more particularly concerns a methodof and a machine for making envelopes of the tive-seal or the like shapeor size -according to which selectively either the respective uppermostor the respective lowermost sheet of a stack of sheets is withdrawn withor without simultaneous formation of a fold. This method as heretoforepracticed has the drawback that a spacing between the smallest andlargest size to be worked is unavoidable so that the output per timeunit is relatively limited. Moreover the heretoyfore known method doesnot make it possible to work the envelopes in such close succession thatthere is practically an uninterrupted track of closely succeedingenvelopes passing by the respective treatment stations.

IIt is, therefore, an object of this invention to provide a method ofand machine for making envelopes which will overcome the abovement-ioned drawbacks.

`Numerous and various methods have been applied heretofore` for makingenvelopes with gummed closure ilaps. Iny this connection, there are usedmachines which work from a sheet, and there are also machines which workfrom a r-oll. With regard to the folding and pasting of the letterenvelopes it may be mentioned that with the said two types of machines,the said working steps are carried out after the paper has been cut intoblanks of predetermined size. With both manufacturing methods it isknown prior, as well as after the folding step, to provide the blankswith adhesive or the like for the later pasting of the closure flaps. Inorder to dry said gummed closure flaps, it was heretofore necessary toemploy a rather long drying path; in particular with high speed machineshaving high output, it was necessary in view of the high paper speed toincrease the drying path more and more. This in turn required larger andlarger desi-gus of the drying devices in the shape of 1conveyor belts orconveyor chains. On the other hand, with these long drying pathsespecially when using conveyor belts, shifting of the work piecesfrequently occurred which harmfully affected the folding process.

It is,therefore, another objectV of this invention to provide a methodof and machine for making envelopes with gummed closure aps which willreduce to a minimumthe drying period for the adhesive applied to thepaper surface so that, even with a maximum output and a maximum paperspeed, only a very short drying path will be required. Y

It is still another object of this invention t-o provide a method of andmachine for making envelopes from precut sheets of paper which, whilebeing rather simple, is high-ly economical, eicient and easily to berealized.

These and other objects and advantages of the invention will appear moreclearly from the following specification in connection with theaccompanying drawings in which: v

Fig. 1 diagrammatically illustrates the principle of a first methodaccording to the invention.

Fig. 2 diagrammatically illustrates a method which is somewhat modifiedover that of Fig. 1.

States Patent mice what modified over that of Fig. 3 for carrying outthe method according to Fig. 2.

Fig. 8 is a plan view of the side flap folding devices.

General arrangement The essence of the invention consists `in that theblanks cut to a predetermined size and withdrawn from a stack of blanksare passed by the treatment stations in au overlapping or fanned outmanner. These blanks or work pieces, while being in the saidarrangement, have, according to the new method, applied the adhesive orgum for the later pasting of the closure flaps, whereupon after eifecteddrying, the folding, turning over and gumming of the aps extendingtransverse to and in the conveying direction, is effected in such amanner that an uninterrupted paper train is formed, the wor-k pieces ofwhich subsequently by the turning-over step and closing of the closureflaps are separated into individual finished work pieces.

The employment of the method, according to the I present invention, i.e. the arrangement of a staggered paper layer according to massproduction methods for purposes of folding and pasting has considerableadvantages over the heretofore known methods. According to the presen-tinvention, depending on the width of the staggering, simultaneously amore or less great number of work pieces can be subjected to the foldingand gumming process. With reference to the length of the blanks in theconveying direction, according to the present invention, the heretoforecustomary inter-spaces between the smallest and largest sizes to beWorked, are completely eliminated since the Work pieces are subjected tothe folding step in an uninterrupted sequence. This results in aconsiderable increase of the output without increasing and acceleratingthe working tools while the paper blanks may move at a minimum speed.vAccording to the present invention, a conveyor is provided forconveying the work pieces which conveyor has its outer surfaces providedwith an elastic adhesion-creating mass. As support for said conveyor, aslide rai-l or guiding rail may be provided which presses the workpieces carried by said conveyor against the latter so that the workpieces will be passed through t-he machine in a safe manner withoutchanging their position relative to said conveyor.

The present invention furthermore comprises a method of depositing anddrying the paste or gum on the closure v aps. According to this newmethod, the paper sheets to be provided with paste or gum at the variousclosure flaps, are prior to the application of such paste or gum, driedin any convenient manner so that the humidity contained in the papersheets will be evaporated. This method makes it possible thatimmediately following the evaporation process, paste or gum can beapplied to said paper sheets and said paste or gum will immediatelyharden on the paper surface and due to the heat radiation of the heatedpaper will immediately and completely dry. The advance in the art asbrought about by the present invention consists in that, even with amaximum output and at a maximum paper speed, only a very short dryingpath will be required for the drying period.

Structural arrangement Referring now to the drawings and Figs. l and 3thereof in particular, the respective lowermost sheet or blank patentedMay 7, 1951 whenthe withdrawal is effected, first ,the closure ap 51isfolded over so that the latter willrest on what will `later form theaddress side of the envelope. The thus staggered blanks overlapping eachother and provided with a turned over closure flap are successivelypassed upon .a pair of belts or bands 6, 7 (see Figs. 3 and 6). The saidbelts or bands carried by pulleys 31, 32 carry the echeloned or`overlappingwork pieces 4 incooperation with the. guiding rails4 8, 9during the gumming and dryingv Between said conveyor belts or bands 6,7' (Figs. 3 and 6),` there is provided a heating chamber 10' process.

in which are arranged heating tubes 11.- When the train of overlappingwork pieces 4, by means of the Conveyor belts 6, 7, is passed over theheating chamber 10, the said echeloned or overlapping work pieces are,according to the present invention, heated to such an extent that thegum or paste 12 subsequently applied to said work pieces bya gummingdevice 13 will immediately harden on the paper surface and will, due tothe heat radiation of the train of work pieces itself, completely dry.On its further way over the heating chamber 10, the work pieces 4 are.passed onto the conveyor belt 14; The conveyor belt 14 is, according tothe present invention, designed similar to the conveyor belts 6, 7 andhas its outer surface provided'withv an elastic adhesion-creating massas, for instance, rough rubber, sponge rubber or cellulose sponge.

When the work pieces 4 enter between the conveyor belt' 14 and theguiding rail 15, the work pieces are by means of the guiding rail 15Tpressed against the conveyor beltV 14 and are carried through themachine While the work pieces slide `along said guiding rail 15.Laterally of the conveyorbelt 14, there are arranged folding knives 16and folding loops `17. While the train or overlapping work pieces f4 ispassed through the folding knives 16 and folding loops 17, those twoflap portions18 ofeachV work piece 4which stick out from the centralportion of the workpiece in a direction transverse to the conveyingdirection, are foldedover so that an `uninterrupted train is formed madeup of the individual'work pieces cachot which has already-three folds.pieces leaves the conveyor belt 14 and the guiding rail 15,` it enterslbetween the delivery rollers 19, 20. Onthe upper roller20 there areprovided gum or pasteapplying means which receive the paste or gum from`a device 21 arranged thereabove for pasting the bottom ilap 24.

As soon as the leading folding edge 22'passes below the contact point ofthe two delivery rollers 19,' 29, the respective leading work piece 25istat an increased speed separated from the entering train of-workpieces because the rollers V19, 20 have a higher speed than the belt.14. Simultaneously the work piece is provided with the paste orgum 23for pasting thebottom ap 24. The two delivery rollers 19,` 20 feed thework piece 25 provided with three folds into the folding pocket 26 sothat while the direction of movement is being reversed, the bottom flap24 is folded over and is pasted to thetwo lateral flaps 13. Whcn thework piece passes through the rollers 19, Z0, the closure hap 5 whichwas folded over during the with drawal of the respective sheet from thepile of sheets 1. is caught by the suction roller 27, is opened and ispassed between the `rollers 27 and 2S. The roller 27 feeds the nowleading closure flap. 5 through guiding means 30 while the work pieceiscaught by the lower suction roller 28 directly behind the folding edge29 and by the guide 30is started upwhile the closure flap 5 is beingclosed.

Accordingutothefmcthod illustratedin Fig. 2, thewitlr When the train ofwork drawal and folding of the work pieces is effected in a mannersimilar to that of the method according to Fig. 1. Therefore, the samereference numerals as in Fig. 1 have been employed in Fig. 7illustrating the machine for carrying out the method of Fig. 2. However,the reference numerals employed in Fig. 7 and designating partscorresponding to those of Fig. 3 are provided with the same referencenumerals as employed in Fig. 3 with the addition of the sutix 11. Aswill be seen from Figs. 2 and 7, the method and arrangement respectivelyillustrated therein differ from that of Figs. l and 3 in that the pasteor gum is applied to the closure flaps subsequent to the folding step.According to Figs. 2 and 7, an envelope is made by subjecting the blanksdirectly to the folding process while the work pieces, when they arewithdrawn from the stack 1a, are simultaneously staggered or tanned out.The preliminary breaking, the folding over and the gummingis carried outin the same succession as referred to in Fig. l. The thus-formed trainis then divided up into individual pieces in `such a manner that theindividual work piccesare staggered with regard to each other in anoverlapping manner and in this position are conveyed together.

The thus-formed paper track is, according tothe present invention,heated by any convenient means such as the heating drum 10a .(Fig. 7)whereupon the paste or gum is-applied to the'closure aps. has beencompleted, the closure flaps are closed while thc workipieces arecollected andstacked up toa stack.

As for as.` the principleof the invention is concerned, it is immaterialwhether the pre-cut sheets or blanks are withdrawn from the-stack ofsheets Withor without the simultaneous formation of a fold. Theinvention may also be applied where the withdrawal of the sheets iseffected with open unfolded sheets.

It yis furthermoreto be understood that the present invention-is, 'by'noimeans, limited to the particular methods and devices described in thepreceding specification with regard to the'accompanying drawings, butalso cornprises any modifications-within the scope of the appendedclaims.`

What I claim is:

1. A- method of making envelopes from sheets arranged in a stack `andcutto size with corner portions thereof cut to respectively form the side,bottom and closure flaps, Which'includes the steps of: withdrawingfromsaidstackvina continuous process one sheet after another whileadvancing said sheets in superimposed but staggered'position so thatsaid sheets overlap each other in the direction of advancement ofsaidsheets; heating saidsheets while they are thus being advanced; applying`adhesive 'to that portion of said heated sheets which will formAthe-closure flap; drying the thus applied adhesive; subsequentlyfolding at least those portions of 'said sheets which form theside-flapsof the envelopes while simultaneously advancing the thusfolded sheets in superimposed ,and overlapping*l condition; segregatingthe" individual folded sheets from 'each other; applying adhesive tomargirial portions ofthe` side flaps of said segregated and foldedsheets; folding over the bottom flaps of said segregated-andA foldedsheets while pressing the same against said side flaps; and subsequentlyfolding the closure flaps so that they will lie on the back side of theenvelopes.

2. A method of making .envelopes from sheets arranged in a stackand cutto size with corner` portions thereof cutto respectively form the side,bottom and closure aps, which includes the steps of: withdrawing fromsaid stack in `a continuous process one sheet after anotherwhileadvancing said sheets in superimposed but staggered position so'that said sheets overlap cach other in the direction of advancement ofsaid sheets while thus advancing'said sheets folding at least thosesheet portions which form the side flaps of the envelopes to be made;heating the thus-folded sheets; applying adhesive to that portion ofsaid sheets which will form the closure flaps; drying After the dryingprocess` the thus-applied adhesive; applying additional adhesive t0those porti-ons of said sheets which will form the side and bottomportion of the envelopes; and pressing said side and bottom flapsagainst each other so as to connect the same together.

3. An arrangement for making envelopes, which -includes a rotatabledrum, heating means arranged within said drum for heating the same,iirst conveying means provided with elastic gripping means and arrangedto convey in overlapped relationship pre-cut paper sheets to be madeinto envelopes over said drum over a predetermined arc thereof forheating said sheets, means arranged `adjacent the periphery of said drumintermediate the end points of said arc and a considerable distan-ceaway from the starting point of said arc for applying adhesive means tothat portion of each sheet passing over said drum which Will form theclosure portion of the respective envelope, second conveying meansadjacent said drum for receiving in overlapped relationship the sheetspassed over ysaid arc of said drum, folding means arranged adjacent toand laterally of said second conveying means for folding portions ofsaid sheets while in said overlapped relationship into side flaps of therespective envelope, roller means arranged adjacent that end of saidsecond conveying means which is remote from said drum to receive thefolded sheets from said second conveying means, sa-id roller meanshaving a rotational speed greater than the speed 4of said secondconveying means to thereby segregate the individual folded sheets fromeach other, paste-applying means adjacent said roller means for applyingpaste to that portion of said sheets which will form the bottom flap ofthe respective envelope, and folding means for folding said bott-om flapand fastening the same to `sa-id side ilaps.

References Cited in the le of this patent UNITED STATES PATENTS 232,777Sutton Sept. 28, 1880 890,114 Wing .lune 9, 1908 1,557,534 Swab Oct. 13,1925 1,807,867 Novick June 2, 1931 2,354,351 Schuetz July 25, 19442,359,825 Campbell Oct. 10, 1944 2,568,629 Heywood Sept. 18, 1951 FOREGNPATENTS 626,262 Germany Feb. 22, 1936

